Normally, electrically operated starters are used for starting internal combustion engines. In large engines having several tens or hundreds of liters of displacement such as, for example, marine engines, it is known to connect a plurality of starters in parallel to be able to provide the high starter power.
FIG. 1 shows a parallel starting system from the related art having two starters 1a, 1b. Each of the starters includes a starter motor 2a, 2b and an engaging relay 4a, 4b which normally performs two functions. On the one hand, engaging relay 4a, 4b engages a pinion (not shown) driven by starter motor 2a, 2b with a ring gear of the internal combustion engine. On the other hand, engaging relay 4a, 4b closes a primary current path 8 via a normally open contact 5a, 5b when the pinion has engaged with the ring gear. This begins the actual starting operation.
To prevent one of the two starters 1a, 1b from beginning the starting operation earlier than the other, both starters 1a, 1b are interconnected in such a way that primary current path 8 to starter motors 2a, 2b is not closed until both pinions are engaged or both engaging relays 4a, 4b have completely pulled up. The two engaging relays 4a, 4b are in this case connected in parallel with respect to their control terminal and are connected to a terminal 50 which is connected to the starter switch (switch 6). The load terminals (terminals 30, 30b) of engaging relays 4a, 4b are, however, interconnected in series. Terminal 30 of first starter 1a is connected to a battery which supplies it a voltage U+.
In a starting operation, i.e., after ignition 6 is activated, windings HW (holding winding) and EW (pull-in winding) of engaging relays 4a, 4b are supplied with current. As a result, both engaging relays 4a, 4b pull in, switches 5a, 5b being closed. When both switches 5a, 5b are closed, both starter motors 2a, 2b are supplied with current simultaneously and start the internal combustion engine. It is a disadvantage in this case that both engaging relays 4a, 4b must switch and conduct the same current for both starter motors 2a, 2b. Noise-contaminated actuating signals (signal bounce) can therefore result in high contact erosion and a high risk of contact welding exists.